delete expirable LRU Close method

README.md

@@ -47,8 +47,7 @@ import (
 func main() {
 	// make cache with 10ms TTL and 5 max keys
 	cache := expirable.NewLRU[string, string](5, nil, time.Millisecond*10)
-	// expirable cache need to be closed after used
-	defer cache.Close()
+
 
 	// set value under key1.
 	cache.Add("key1", "val1")

expirable/expirable_lru.go

@@ -47,7 +47,7 @@ const numBuckets = 100
 //
 // Providing 0 TTL turns expiring off.
 //
-// Delete expired entries every 1/100th of ttl value.
+// Delete expired entries every 1/100th of ttl value. Goroutine which deletes expired entries runs indefinitely.
 func NewLRU[K comparable, V any](size int, onEvict EvictCallback[K, V], ttl time.Duration) *LRU[K, V] {
 	if size < 0 {
 		size = 0
@@ -71,8 +71,10 @@ func NewLRU[K comparable, V any](size int, onEvict EvictCallback[K, V], ttl time
 		res.buckets[i] = bucket[K, V]{entries: make(map[K]*internal.Entry[K, V])}
 	}
 
-	// enable deleteExpired() running in separate goroutine for cache
-	// with non-zero TTL
+	// enable deleteExpired() running in separate goroutine for cache with non-zero TTL
+	//
+	// Important: done channel is never closed, so deleteExpired() goroutine will never exit,
+	// it's decided to add functionality to close it in the version later than v2.
 	if res.ttl != noEvictionTTL {
 		go func(done <-chan struct{}) {
 			ticker := time.NewTicker(res.ttl / numBuckets)
@@ -270,16 +272,16 @@ func (c *LRU[K, V]) Resize(size int) (evicted int) {
 }
 
 // Close destroys cleanup goroutine. To clean up the cache, run Purge() before Close().
-func (c *LRU[K, V]) Close() {
-	c.mu.Lock()
-	defer c.mu.Unlock()
-	select {
-	case <-c.done:
-		return
-	default:
-	}
-	close(c.done)
-}
+// func (c *LRU[K, V]) Close() {
+//	c.mu.Lock()
+//	defer c.mu.Unlock()
+//	select {
+//	case <-c.done:
+//		return
+//	default:
+//	}
+//	close(c.done)
+// }
 
 // removeOldest removes the oldest item from the cache. Has to be called with lock!
 func (c *LRU[K, V]) removeOldest() {

expirable/expirable_lru_test.go

@@ -68,7 +68,6 @@ func BenchmarkLRU_Freq_NoExpire(b *testing.B) {
 
 func BenchmarkLRU_Rand_WithExpire(b *testing.B) {
 	l := NewLRU[int64, int64](8192, nil, time.Millisecond*10)
-	defer l.Close()
 
 	trace := make([]int64, b.N*2)
 	for i := 0; i < b.N*2; i++ {
@@ -94,7 +93,6 @@ func BenchmarkLRU_Rand_WithExpire(b *testing.B) {
 
 func BenchmarkLRU_Freq_WithExpire(b *testing.B) {
 	l := NewLRU[int64, int64](8192, nil, time.Millisecond*10)
-	defer l.Close()
 
 	trace := make([]int64, b.N*2)
 	for i := 0; i < b.N*2; i++ {
@@ -195,7 +193,6 @@ func TestLRUEdgeCases(t *testing.T) {
 
 func TestLRU_Values(t *testing.T) {
 	lc := NewLRU[string, string](3, nil, 0)
-	defer lc.Close()
 
 	lc.Add("key1", "val1")
 	lc.Add("key2", "val2")
@@ -207,17 +204,16 @@ func TestLRU_Values(t *testing.T) {
 	}
 }
 
-func TestExpirableMultipleClose(_ *testing.T) {
-	lc := NewLRU[string, string](10, nil, 0)
-	lc.Close()
-	// should not panic
-	lc.Close()
-}
+// func TestExpirableMultipleClose(_ *testing.T) {
+//	lc := NewLRU[string, string](10, nil, 0)
+//	lc.Close()
+//	// should not panic
+//	lc.Close()
+// }
 
 func TestLRUWithPurge(t *testing.T) {
 	var evicted []string
 	lc := NewLRU(10, func(key string, value string) { evicted = append(evicted, key, value) }, 150*time.Millisecond)
-	defer lc.Close()
 
 	k, v, ok := lc.GetOldest()
 	if k != "" {
@@ -299,7 +295,6 @@ func TestLRUWithPurge(t *testing.T) {
 
 func TestLRUWithPurgeEnforcedBySize(t *testing.T) {
 	lc := NewLRU[string, string](10, nil, time.Hour)
-	defer lc.Close()
 
 	for i := 0; i < 100; i++ {
 		i := i
@@ -370,7 +365,6 @@ func TestLRUInvalidateAndEvict(t *testing.T) {
 
 func TestLoadingExpired(t *testing.T) {
 	lc := NewLRU[string, string](0, nil, time.Millisecond*5)
-	defer lc.Close()
 
 	lc.Add("key1", "val1")
 	if lc.Len() != 1 {
@@ -484,8 +478,6 @@ func TestLRURemoveOldest(t *testing.T) {
 func ExampleLRU() {
 	// make cache with 10ms TTL and 5 max keys
 	cache := NewLRU[string, string](5, nil, time.Millisecond*10)
-	// expirable cache need to be closed after used
-	defer cache.Close()
 
 	// set value under key1.
 	cache.Add("key1", "val1")

simplelru/lru.go

@@ -163,9 +163,6 @@ func (c *LRU[K, V]) Resize(size int) (evicted int) {
 	return diff
 }
 
-// Close does nothing for this type of cache.
-func (c *LRU[K, V]) Close() {}
-
 // removeOldest removes the oldest item from the cache.
 func (c *LRU[K, V]) removeOldest() {
 	if ent := c.evictList.Back(); ent != nil {